1. Field of the Invention
This invention relates generally to vehicle anti-theft devices, and more particularly to vehicle anti-theft locks.
2. Description of the Prior Art
Vehicle theft is a continuing problem but is of the utmost concern to the owners of heavy equipment such as bulldozers, graders, loaders, tractors, and other heavy machinery using diesel engines as a power source. Heavy equipment is difficult to transport back to the equipment yard on a daily basis and, therefore, is usually left on the jobsite unattended.
Past attempts to offer an anti-theft device for heavy equipment have been limited to either interruption of the electrical system through a keyed switch in the operator's compartment or to cutting off fuel flow in the fuel system. Both methods can be overcome by thieves, who often are skillful at bypassing the cutoff device. Additionally, because thieves often have direct access to the cutoff device, they sometimes are able to disarm the cutoff device itself so that bypassing the device is not necessary.
This Applicant's pending U.S. Patent Application Ser. No. 081,888 describes a vehicle anti-theft device for heavy equipment powered by engines with an external governor linkage lever, in which the linkage lever is locked against movement to prevent operation of the engine. A lock housing prevents access to the lindage lever. There are a number of vehicles and other heavy equipment in which an external governor linkage lever can not be used to stop operation of the engine. Particularly, many engines utilize a fuel pump and governor assembly in which an electrically controlled shut-off solenoid is utilized to cease operation of the engine. A typical electrical control circuit for such an engine includes, in series, the main battery of the engine or an alternate power supply, a keyed switch in the operator's compartment, and the shut-off solenoid. This invention is particularly directed to the prevention of theft or unauthorized operation of these types of vehicles and engines, and to engines with alternative electrical fuel control systems.